The present invention relates generally to rotary heat exchangers and, more specifically, to heat exchange baskets for such rotary heat exchangers.
A rotary regenerative heat exchanger is employed to transfer heat from one hot gas stream, such as a flue gas stream, to another cold gas stream, such as combustion air. The rotor contains a mass of heat absorbent material which is first positioned in a passageway for the hot gas stream where heat is absorbed by the heat absorbent material. As the rotor turns, the heated absorbent material enters the passageway for the cold gas stream where the heat is transferred from the absorbent material to the cold gas stream.
In a typical rotary heat exchanger, such as a rotary regenerative air preheater, the cylindrical rotor is disposed on a central rotor post and divided into a plurality of sector-shaped compartments by a plurality of radial partitions, known as diaphragms, extending from the rotor post to the outer peripheral shell of the rotor. These sector shaped compartments are loaded with modular heat exchange baskets which contain the mass of heat absorbent material commonly comprised of stacked plate-like elements.
The conventional heat exchange basket comprises a frame which is open on each end and which has side walls which may have covers. The baskets are subject to radial deformation between the hot and the cold faces of the basket and along the chord width of the outboard basket cover. This deformation is caused by the element packing pressure. Such deformation can become a problem when tight dimensional tolerances are required for basket installation into the compartments. In addition, such deformation may cause interference between adjacent baskets or with the rotor structure. Where such deformation is unacceptable, conventional baskets utilize frame components and covers have been fabricated from heavier gauge materials to resist the force exerted by the heat exchange elements. Such basket structure adds excess weight to the rotor and compromises heat transfer surface area.